Suchergebnisse

The work presents the results of paleogeographic study, including facies-lithological, malacofaunistic and luminescence analyses, of three boreholes core drilled in the central part of the Manych Depression, which made it possible to determine the time and stages of the existence of the Karangatian ingressive bay in the Manych Depression, and to correlate the latter with phases of the Karangatian transgression identified earlier on the basis of luminescence dating. Based on the results of the study it was found that: 1) the Karangatian Sea penetrated into the Manych Depression during the second phase of transgression in the time interval of ~120-110 ka years ago (MIS 5e-d). The salinity of the bay in the area of the modern Manych-Gudilo Lake reached 20-22‰; 2) the inflow of water of the Hyrcanian transgression of the Caspian into the bay in the central part of the Manych Depression took place 110-105 ka years ago, which corresponds to the third phase of the Karangatian transgression (MIS 5c). The brackish Caspian waters desalinated the Karangatian Bay in the area of the modern Manych-Gudilo Lake down to 14‰ and below; 3) the waters of the Karangatian Sea finally left the Manych Depression about 105 ka years ago (MIS 5c).

Biostratigraphic analysis of the cores from the Black Sea shelf in the northeastern part of the basin showed that the exposed Karangatian deposits contain shells of Didacna cristata and Didacna subcatillus mollusks in their upper part. The didacnae are of Caspian origin: they are characteristic species of the Hyrcanian transgressive basin that developed in the Caspian at the beginning of the Late Pleistocene. Mollusks migrated to the Karangatian Basin of the Black Sea through the strait that opened in the Manych Depression when the level of the Hyrcanian transgression overreached the threshold of the Manych runoff. The waters of the strait flowed into the Karangatian Basin in the final phase of its development when the sea level was lower than nowadays and salinity didn't exceed 18‰.